1.They are happpy because they have done the experiment successfully.They have made up their minds to tell the wodld about the result of their experiment.
2.This is second time that i have lost my mobile phone.
3.The students have been preparing for the New Year's concert since last month.They have invited their parents to come and watch their performance.
4.For the last two years,he has been writing a book on the Second World War, but he hasn't finished it yet.
5.I wonder if Mary has forgetten my number.I have been expecting her to call me for the past two hours.
6.I have been waiting for an hour but he still hasn't turned up.
7.It has snowing for three days. We have had too much snow this winter.
8.I have been tring to talk to him on the phone for weeks but I have got no answer yet. What has happend to him.
8.Professor Wang has doing the research on English literature for more than 30 years.He has written more than 10 books,some of which have been published in England and the USA in recent yeas.Now he is teaching English literature in a famous university.
9.Professor Wang's books have become quite popular since the 1990s.Many people wrote to him after reading his books,asking various questions about English literature.
10.I e-mailed,Professor Wang last week,asking some questions that had puzzled me.To my surpris,he answered me yesterday,saying that he was coming to my school to give us a talk today.My classmates and I have been expecting his visit since we got the news.